Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival

To better understand and predict Oregon coho (Oncorhynchus kisutch) marine survival, we developed a conceptual model of processes occurring during four sequential periods: (1) winter climate prior to smolt migration from freshwater to ocean, (2) spring transition from winter downwelling to spring/summer upwelling, (3) the spring upwelling season and (4) winter ocean conditions near the end of the maturing coho’s first year at sea. We then parameterized a General Additive Model (GAM) with Oregon Production Index (OPI) coho smolt-to-adult survival estimates from 1970 to 2001 and environmental data representing processes occurring during each period (presmolt winter SST, spring transition date, spring sea level, and post-smolt winter SST). The model explained a high and significant proportion of the variation in coho survival (R 2 ¼ 0.75). The model forecast of 2002 adult survival rate ranged from 4 to 8%. Our forecast was higher than predictions based on the return of precocious males (‘jacks’), and it won’t be known until fall 2002 which forecast is most accurate. An advantage to our environmentally based predictive model is the potential for linkages with predictive climate models, which might allow for forecasts more than 1 year in advance. Relationships between the environmental variables in the GAM and others (such as the North Pacific Index and water column stratification) provided insight into the processes driving production in the Pacific Northwest coastal ocean. Thus, coho may be a bellwether for the coastal environment and models such as ours may apply to populations of other species in this habitat.

[1]  Steven R. Hare,et al.  Decadal-scale regime shifts in the large marine ecosystems of the North-east Pacific: a case for historical science , 1994 .

[2]  C. Coronado,et al.  Spatial and temporal factors affecting survival in coho salmon (Oncorhynchus kisutch) in the Pacific Northwest , 1998 .

[3]  Russ E. Davis,et al.  Monthly Mean Sea-Level Variability Along the West Coast of North America , 1982 .

[4]  J. Skalski,et al.  Multivariate regression relationships between ocean conditions and early marine survival of coho salmon (Oncorhynchus kisutch) , 1999 .

[5]  A. Bakun.  Patterns in the ocean: Ocean processes and marine population dynamics , 1996 .

[6]  Randall M. Peterman,et al.  Spatial correlation patterns in coastal environmental variables and survival rates of salmon in the north‐east Pacific Ocean , 2002 .

[7]  A. Huyer,et al.  Variations in the alongshore correlation of sea level along the West Coast of North America , 1978 .

[8]  R. Beamish,et al.  Pacific salmon production trends in relation to climate , 1993 .

[9]  R. Brodeur,et al.  Long-term variability in zooplankton biomass in the subarctic Pacific Ocean , 1992 .

[10]  W. Pearcy.  Marine nekton off Oregon and the 1997–98 El Nino , 2002 .

[11]  W. Pearcy,et al.  Growth of Juvenile Coho Salmon (Oncorhynchus kisutch) off Oregon and Washington, USA, in Years of Differing Coastal Upwelling , 1988 .

[12]  E. L. Brannon,et al.  Ocean Ecology of North Pacific Salmonids , 1993 .

[13]  Robert L. Smith,et al.  The spring transition in currents over the Oregon Continental Shelf , 1979 .

[14]  J. Cole.  Coastal sea surface temperature and coho salmon production off the north-west United States , 2000 .

[15]  D. Scarnecchia.  Effects of Streamflow and Upwelling on Yield of Wild Coho Salmon (Oncorhynchus kisutch) in Oregon , 1981 .

[16]  A. Schoener,et al.  Changes in the marine biota coincident with the 1982–1983 El Niño in the northeastern Subarctic Pacific Ocean , 1987 .

[17]  R. Waples,et al.  Status review of chum salmon from Washington, Oregon, and California , 1995 .

[18]  J. Koslow,et al.  Climate variability and marine survival of coho salmon (Oncorhynchus kisutch) in the Oregon production area , 2002 .

[19]  Richard J. Beamish,et al.  The regime concept and natural trends in the production of Pacific salmon , 1999 .

[20]  Robert L. Smith,et al.  Seasonal cycles of currents, temperatures, winds, and sea level over the northeast pacific continental shelf: 35°N to 48°N , 1987 .

[21]  Steven R. Hare,et al.  Inverse Production Regimes: Alaska and West Coast Pacific Salmon , 1999 .

[22]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[23]  J. Simpson.  An offshore eddy in the California current system part III: Chemical structure , 1984 .

[24]  Trevor Hastie,et al.  Statistical Models in S , 1991 .

[25]  James W. Hurrell,et al.  Decadal atmosphere-ocean variations in the Pacific , 1994 .

[26]  Beamish,et al.  Trends in coho marine survival in relation to the regime concept , 2000 .

[27]  A. Gargett.  The optimal stability `window': a mechanism underlying decadal fluctuations in North Pacific salmon stocks? , 1997 .

[28]  Robert L. Smith,et al.  The signature of El Niño off Oregon, 1982–1983 , 1985 .

[29]  Nicholas E. Graham,et al.  The 1976-77 Climate Shift of the Pacific Ocean , 1994 .

[30]  P. Strub,et al.  Altimeter-derived variability of surface velocities in the California Current System: 2. Seasonal circulation and eddy statistics , 2000 .

[31]  D. Mackas,et al.  Changes in the zooplankton community of the British Columbia continental margin, 1985-1999, and their covariation with oceanographic conditions , 2001 .

[32]  Pablo A. Bilbao.  Interannual and interdecadal variability in the timing and strength of the spring transitions along the United States west coast , 1999 .

[33]  G. Mitchum,et al.  Decadal and basin-scale variation in mixed layer depth and the impact on biological production in the Central and North Pacific, 1960-88 , 1995 .

[34]  L. Holtby,et al.  Importance of Smolt Size and Early Ocean Growth to Interannual Variability in Marine Survival of Coho Salmon (Oncorhynchus kisutch) , 1990 .

[35]  W. Pearcy,et al.  MIGRATIONS OF COHO SALMON, ONCORHYNCHUSKlSUTCH, DURING mEIR FIRST SUMMER IN mE OCEAN , 1988 .

[36]  R. Beamish,et al.  Climate change and northern fish populations , 1995 .

[37]  T. Nickelson,et al.  Influences of Upwelling, Ocean Temperature, and Smolt Abundance on Marine Survival of Coho Salmon (Oncorhynchus kisutch) in the Oregon Production Area , 1986 .

[38]  J. Lichatowich,et al.  Salmon Without Rivers: A History Of The Pacific Salmon Crisis , 1999 .

[39]  H. Akaike.  A new look at the statistical model identification , 1974 .